U.S. Pat. No. 3,503,925 (P. A. Griffin, published on 31 March 1970 to Midland Silicones Ltd.) describes a process for preparing a cross-linkable organopolysiloxane resin using an organopolysiloxane resin which contains less than 0.25% by weight of silanol groups. This organopolysiloxane resin is mixed with an anhydrous, quaternary ammonium silanolate or phosphonium silanolate as condensation catalyst. Due to the low silanol content of the organopolysiloxane resin, this mixture does not have a tendency to gel and therefore has a long shelf life. Crosslinking of the organopolysiloxane resin is obtained by heating the mixture above 50.degree. C. on the substrate.
U.S. Pat. No. 2,986,549 (J. R. McLoughlin et al., published on 30 May 1961 to General Electric Co.) describes coating compositions based on silicone resins. These resins are prepared, inter alia, by hydrolysis and condensation of phenyltrichlorosilane and dimethyldichlorosilane and are mixed with tetramethylammonium hydroxide as a condensation catalyst and with from two to five mols of acetic acid per mol of tetramethylammonium hydroxide to form a coating composition. The acetic acid serves as stabilizer for storage of the coating composition. The actual coating is formed by heating the coating composition on the substrate, during which the stabilizer softens and curing is facilitated.
Similar coating compositions are described in U.S. Pat. No. 2,986,548 (J. R. McLoughlin et al., published on 30 May 1961 to General Electric Co.). However, the alkaline condensation catalyst employed need not be completely neutralized by means of acid if an .alpha.-halogenated carboxylic acid, such as trichloroacetic acid, is added in amounts of at least 0.25 mol per mol of the alkaline condensation catalyst.
Therefore, it is an object of the present invention to provide coating compositions having a long shelf life. Another object of the present invention is to provide binders which physically dry or crosslink in a short period of time, even at room temperature, to form tack-free films. Still another object of the present invention is to provide coatings which may be applied and exposed to high temperatures. A further object of the present invention is to provide coating compositions which may be used to form baked finishes.